Most often, they warranty the part but not the labor.All I have ever seen them do is find some disclaimer and weasel. I will see if I can find anyone who had had rust bubbling paint fixed at a body shop and had them fix it for free when it comes back.
Probably like the "lifetime muffler" at shops.
Sure the muffler is free, but this pipe it goes onto is too weak to weld too etc or this small piece has to be repaired...money please.
Paint - $2.50
Labor - $500